The MPI injection system has a two-piece switchable intake manifold, while the MPFI system has a three-piece non-switchable plastic intake manifold. In addition, the MPFI system no longer requires a mass air flow meter.
Fuel is sucked from the fuel tank by an electric pump and fed through the fuel filter to the dispenser, which is made in the form of an annular fuel line, and then to the valve injectors. The pressure regulator at the end of the dispenser keeps the fuel pressure in the system constant.
Valve injectors sequentially inject fuel into the intake manifold ahead of the intake valves. Injection is not carried out simultaneously. This means that the injectors are decoupled, controlled individually and inject fuel according to a sequence of flashes ahead of the engine intake valves. By choosing the start of injection in relation to the opening times of the intake valves, the power and environmental qualities of the engine can be better controlled. In addition, the throttle response of the engine is improved.
In contrast to the KE injection system, the MPI system has an air mass meter instead of a volume flow meter. Such a meter has the following advantages: small dimensions, automatic equalization of the influence of temperature and altitude, no moving parts and therefore little wear.
In the mass flow meter, the electrically heated filament is cooled by the flowing intake air. In order to keep the temperature of the hot filament constant, the filament current varies according to the amount of air flowing. By changing the glow current, the control unit determines the load mode of the engine and, in accordance with this, regulates the amount of injected fuel. To avoid distortion due to dirt, each time the motor is switched off, the filament glows automatically.
The control unit, in accordance with the signal from the mass air flow meter and the crankshaft speed, regulates the duration of the injection, and thus the amount of injected fuel. With a longer opening of the valve injector, more fuel is injected. Additional sensors and converters ensure that the amount of injected fuel is measured correctly in any driving situation.
Visitor comments